Such machine assemblies are used, for example, in motor-vehicle rear-axle differentials that have a pinion shaft supported in a housing. In these assemblies, the two tapered roller bearings are held at a defined spacing using spacer sleeves. It is important for the proper functioning of such an assembly that the two tapered roller bearings (usually positioned in an O-arrangement) be adjusted as precisely as practicable to a predefined axial preload. If the axial preload is too low, gear meshing problems can result, and this can lead to an increased noise level and increased gear wear. Too high a preload, on the other hand, leads to greater bearing friction, which manifests itself in, among other things, increased fuel consumption.
During a running-in or breaking in period of a machine or vehicle, various parts of the machine or vehicle may shift or adjust slightly as they settle into their final operating configuration. This may occur, for example, due to smoothening effects of the components involved, and this settling in may be noticeable in various fitted joints in a bearing assembly or machine assembly. After machine or vehicle start-up, (after the break-in period) a not-insignificant portion of an originally-set bearing preload may be lost over time due to this settling.
Since users tend to prefer reduced noise and wear to low friction, bearing preloads are often set to be higher than necessary. Accordingly a bearing preload is set higher than the expected preload decrease (preload loss following an initial period of operation); the consequently higher bearing friction is taken into account until the vehicle is “worn in.” However, since the actual settling does not always correspond to the estimated expected amount of settling, the bearing assembly sometimes operates with an excess preload over the entire service life of the bearing. This disadvantageously results in an ongoing high level of friction and a higher-than-necessary fuel consumption.